1.5" or 2" check valve?

[NW3]

I notice that a number of check valves used in basement sump installations are 1.5" valves with 1.5" to 2" unions/couplings on either end. Any reason to not go with a 2" check valve instead?

Thanks.

 

[Smooky]

My guess would be the cost.

 

[Sponsor]

 

[Sylvan]

Cost for one factor, GPM discharge another consideration, friction loss to be considered

A normal sump pump for clear water can be as small as 11/4" (1.25) for a sewerage ejector 2" - 3" is the normal sizes used